It isn't supposed to happen to girls either!
The difference is in your statement where you said a boy isn't supposed to let it happen. Why do men think they let it happen when so obviously, at least in my husband's case, he had no choice. He suffers with that so.....the I let it happen thing. No amount of reason gets through on this.
Is that what you were asking for? I know in my situation, I don't beat myself over what happened to me by saying "y did I let it happen" I guess that is the difference between men and women. I don't think society expects us (women) to be able to protect ourselves at all times (which is insulting in it's own right) but for some reason men are not ever to allow themselves to be put in a vulnerable position EVEN when they have no choice. All fucked up if you ask me.